- AS BIG AS, IT GETS?
- The Giant Arc is a large-scale structure that spans 3.3 billion light-years. The Giant Arc comprises galaxies, galactic clusters, and gas. The Giant Arc and other giant systems call into question the homogeneity of the universe. We now know that the universe is not homogeneous. The gas pressure and temperature within these mega-structures are constantly changing. At the core, clusters of neutron stars abound. These gigantic structures are rare.
- Great streams of matter blow in on the solar winds. Then, the gravity of the Giant Arc keeps the different matter within the Great Arc.
- Our universe isn’t an isotropic (no direction home) universe. The same in all directions is a relative thing. We don’t know what lies outside our observable universe or beyond that. The velocities of galaxies differ—space-time curves around the matter. Each region varies by the amount of matter (and the resulting bending of space-time). The energy within space pushes galaxies apart faster than gravity can hold them in place. Also, the overall expansion rate grows because the emptier parts of the universe move more quickly than the dense parts. The universe is expanding, with every galaxy beyond the Local Group speeding away from us.
- All galaxies currently beyond 18 billion light-years are forever unreachable by us, no matter how much time passes. From our vantage point, we observe up to 46.1 billion light-years away. In this universe, the energy density is decreasing.
- The universe’s density refers to the amount of matter within a volume of space. Is the universe closed, open, or flat? It depends on who you ask.
- If the universe’s density is significant enough for its gravity to overcome the force of expansion, then the universe will curl into a ball.
- If the universe’s density is low and unable to stop the expansion, space will warp in the opposite direction. This would form an open universe with negative curvature resembling a saddle.
- However, most scientists believe the universe expands in every direction without curving positively or negatively. It is flat.
- We can see 93 billion light-years back. If there is more to see, its light hasn’t arrived yet. Or, the reason no one has witnessed the epoch of galaxy formation is that the ancient starlight, after traveling to us through the expanding fabric of space for so many billions of years, has become stretched. The earlier ultraviolet and visible light wavelengths have stretched out to become infrared radiation. An electromagnetic wave’s amplitude (or height) is proportional to its intensity. Infrared waves have a wavelength 1,000x longer than ultraviolet waves.
- Infrared waves have longer wavelengths than visible light and can pass through dense regions of gas and dust in space with less scattering and absorption. Thus, infrared energy can also reveal objects in the universe that cannot be seen in visible light using optical telescopes.
- Beyond distances of ~14.5 billion light-years, space’s expansion pushes galaxies away faster than light can travel.
- Dark energy, inherent to space itself, never decreases, even as the universe expands.
- As the universe expands, the space between all unbound objects increases.
- Dark energy, inherent to space itself, never decreases, even as the universe expands.
